Recommendations: Make sure the plug has the correct heat Range, Check for clogged air filter or problem in the fuel system or engine management system. Also check for ignition system problems.

ASH DEPOSIT

Symptoms: Light brown deposits encrusted on the side or center electrodes or both. Derived from oil ad/or fuel. Excessive amount may mask the spark, Causing misfiring and hesitation during acceleration.

Recommendations: If excessive deposits accumulate over a short time or mileages, install new valve guide seals to prevent seep-age of oil into the combustion chambers. Also try changing gasoline brands.